The present application relates to the field of radiation imaging systems. It finds particular application to a data acquisition system of a photon counting system, where radiation photons impinging upon a photon counting detector array are counted and/or an energy of respective radiation photons is resolved via the data acquisition system.
Today, radiation imaging systems such as computed tomography (CT) systems, single-photon emission computed tomography (SPECT) systems, projection systems, and/or line-scan systems, for example, are useful to provide information, or images, of interior aspects of an object under examination. Generally, the object is exposed to radiation (e.g., x-ray photons, gamma photons, etc.), and an image(s) is formed based upon the radiation absorbed and/or attenuated by interior aspects of the object, or rather an amount of radiation that is able to pass through the object. Typically, highly dense aspects of the object absorb and/or attenuate more radiation than less dense aspects, and thus an aspect having a higher density, such as a bone or metal, for example, may be apparent when surrounded by less dense aspects, such as muscle or clothing.
Radiation imaging systems typically comprise a detector array having one or more detector cells. Respective detector cells are configured to indirectly convert or directly convert radiation photons impinging thereon into electrical charge which is used to generate an electrical signal. The detector cells are typically “energy integrating” or “photon counting” type detector cells (e.g., the radiation imaging system operates in energy integrating mode or photon counting mode).
Energy integrating type detector cells are configured to integrate the electrical charge generated over a period of time (e.g., at times referred to as a measurement interval) to generate an electrical signal that is proportional to an incoming radiation photon flux rate at a detector cell. Photon counting type detector cells are configured to generate an electrical signal (e.g., a voltage pulse) for respective radiation photons impinging thereon (e.g., where the impact of a radiation photon on a detector cell may be referred to as a detection event). In some embodiments, the electrical signal (e.g., or an amplitude of a voltage pulse) is indicative of an energy of the radiation photon.
While photon counting type detector cells offer advantages over energy integrating type detector cells in some applications, photon counting type detector cells are sensitive to noise. For example, noise introduced by electronics of the photon counting type detector cells may cause the number of detection events to be over counted and/or undercounted. Additionally, radiation photons may physically scatter upon interaction with a radiation detection element of a photon counting type detector cell, causing multiple energy deposits. If the photon counting type detector cell does not accurately reconcile these multiple energy deposits, respective energy deposits may be treated as a separate detection event (e.g., causing detection events to be over counted) and/or the energy of the detection event may not be accurately recorded.